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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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What is the net feedback from clouds?

What the science says...

Select a level... Basic Intermediate

Evidence is building that net cloud feedback is likely positive and unlikely to be strongly negative.

Climate Myth...

Clouds provide negative feedback

"Climate models used by the International Panel on Climate Change (IPCC) assume that clouds provide a large positive feedback, greatly amplifying the small warming effect of increasing CO2 content in air. Clouds have made fools of climate modelers. A detailed analysis of cloud behavior from satellite data by Dr. Roy Spencer of the University of Alabama in Huntsville shows that clouds actually provide a strong negative feedback, the opposite of that assumed by the climate modelers. The modelers confused cause and effect, thereby getting the feedback in the wrong direction." (Ken Gregory)

At a glance

What part do clouds play in your life? You might not think about that consciously, but without clouds, Earth's land masses would all be lifeless deserts. Fortunately, the laws of physics prevent such things from being the case. Clouds play that vital role of transporting water from the oceans to land. And there's plenty of them: NASA estimates that around two-thirds of the planet has cloud cover.

Clouds form when water vapour condenses and coalesces around tiny particles called aerosols. Aerosols come in many forms: common examples include dust, smoke and sulphuric acid. At low altitudes, clouds consist of minute water droplets, but high clouds form from ice crystals. Low and high clouds have different roles in regulating Earth's climate. How?

If you've ever been in the position to look down upon low cloud-tops, perhaps from a plane or a mountain-top, you'll have noticed they are a brilliant white. That whiteness is sunlight being reflected off them. In being reflected, that sunlight cannot reach Earth's surface - which is why the temperature falls when clouds roll in to replace blue skies. Under a continuous low cloud-deck, only around 30-60% of the sunlight is getting through. Low clouds literally provide a sunshade.

Not all clouds are such good sunshades. Wispy high clouds are poor reflectors of sunlight but they are very effective traps for heat coming up from below, so their net effect is to aid and abet global warming.

Cloud formation processes often take place on a localised scale. That means their detailed study involves much higher-resolution modelling than the larger-scale global climate models. Fourteen years on, since Ken Gregory of the dubiously-named Big Oil part-funded Canadian group, 'Friends of Science', opined on the matter (see myth box), big advances have been made in such modelling. Today, we far better understand the net effects of clouds in Earth's changing climate system. Confidence is now growing that changes to clouds are likely to amplify, rather than offset, human-caused global warming in the future.

Two important processes have been detected through observation and simulation of cloud behaviour in a warming world. Firstly, just like wildlife, low clouds are migrating polewards as the planet heats up. Why is that bad news? Because the subtropical and tropical regions receive the lion's share of sunshine on Earth. So less cloud in these areas means a lot more energy getting through to the surface. Secondly, we are detecting an increase in the height of the highest cloud-tops at all latitudes. That maintains their efficiency at trapping the heat coming up from below.

There's another effect we need to consider too. Our aerosol emissions have gone up massively since pre-Industrial times. This has caused cloud droplets to become both smaller and more numerous, making them even better reflectors of sunlight. Aerosols released by human activities have therefore had a cooling effect, acting as a counter-balance to a significant portion of the warming caused by greenhouse gas emissions.

But industrial aerosols are also pollutants that adversely affect human health. Having realised this, we are reducing such emissions. That in turn is lowering the reflectivity of low cloud-tops, reducing their cooling effect and therefore amplifying global warming due to rising levels of greenhouse gases.

It sometimes feels as if we are between a rock and a hard place. We'd have been better off not treating our atmosphere as a dustbin to begin with. But there's still a way to fix this and that is by reducing all emissions.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!


Further details

The IPCC's Sixth Assessment Report eloquently sums up where we are in our understanding of how clouds will affect us in a changing climate:

"One of the biggest challenges in climate science has been to predict how clouds will change in a warming world and whether those changes will amplify or partially offset the warming caused by increasing concentrations of greenhouse gases and other human activities. Scientists have made significant progress over the past decade and are now more confident that changes in clouds will amplify, rather than offset, global warming in the future."

The mistake made by our myth-provider, writing in 2009, was to leap to a conclusion without the information needed in order to do so. He is suggesting that clouds are inadequately represented in climate models, so they must have a negative effect on temperatures. Instead of making such leaps of faith, however, the specialists in cloud behaviour have recognised the challenges and met them square-on. We now know a lot more about clouds as a result.

In the at-a-glance section, we explain the important difference between high clouds and low clouds, agents of warming and cooling respectively. Careful examination of older satellite records has detected large-scale patterns of cloud change between the 1980s and 2000s (Norris et al. 2016). Observed and simulated cloud change patterns are consistent with the poleward retreat of midlatitude storm tracks, the expansion of subtropical dry zones and increasing height of the highest cloud tops at all latitudes. The main drivers of these cloud changes appear to be twofold: increasing greenhouse gas concentrations and recovery from volcanic radiative cooling. As a result, the cloud changes most consistently predicted by global climate models have indeed been occurring in nature.

With respect to the cooling low clouds, one particularly important area of study has involved marine stratocumulus cloud-decks. These are extensive, low-lying clouds with tops mostly below 2 km (7,000 ft) altitude and they are the most common cloud type on Earth. Over the oceans, stratocumulus often forms nearly unbroken decks, extending over thousands of square kilometres. Such clouds cover about 20% of the tropical oceans between 30°S and 30°N and they are especially common off the western coasts of North and South America and Africa (fig.1). That's because the surface waters of the oceans are pushed away from the western margins of continents due to the eastwards direction of Earth's spin on its axis. Taking the place of these displaced surface waters are upwelling, relatively cool waters from the ocean depths. The cool waters serve to chill the moist air above, making its water vapour content condense out into cloud-forming droplets.

 Satellite image of stratocumulus clouds.

Fig. 1: visible satellite image of part of an extensive marine stratocumulus deck off the western seaboard of North America, with Baja California easily recognisable on the right. Image: NASA.

With their highly reflective tops that block a lot of the incoming sunlight, the marine stratocumulus clouds have a very important role as climate regulators. It has long been known that increasing the area of the oceans covered by such clouds, even by just a few percent, can lead to substantial global cooling. Conversely, decreasing the area they cover can lead to substantial global warming.

Although many cloud-types are produced by convection, driven by the heated land or ocean surface, marine stratocumulus clouds are different. They are formed and maintained by turbulent overturning circulations, driven by radiative cooling at the cloud tops. It works as follows: cold air sinks, so that radiatively-cooled air makes its way down to the sea surface, picks up moisture and then brings that moisture back up, nourishing and sustaining the clouds.

Stratocumulus decks can and do break up, though. This happens when that radiative cooling at the cloud tops becomes too weak to send colder air sinking down to the surface. It can also occur when the turbulence that can entrain dry and warm air, from above the clouds into the cloud layer, becomes too strong.

The importance of such processes has been further investigated recently, using an ultra-high resolution model with a 50-metre grid size. (Schneider et al. 2019). Global climate models typically have grid sizes of tens of kilometres. At that resolution, they cannot detail such fine-scale processes. This model, by contrast, is able to resolve the individual stratocumulus updraughts and downdraughts.

 Results of modelling of marine stratocumulus behaviour.

Fig. 2: results of modelling of marine stratocumulus behaviour in a high-CO2 world. This one compares conditions at 400 ppm (present) and 1600 ppm (hopefully never, but relevant to the Palaeocene and Eocene when a super-Hothouse climate prevailed). Redrawn from Schneider et al. 2019.

The modelling shows how oceanic stratocumulus decks become unstable and break up into scattered cumulus clouds. That occurs at greenhouse gas levels of around 1,200 ppm (fig. 2). When that happens, the ocean surface below the clouds warms abruptly because the cloud shading is so diminished. In the model, the extra solar energy absorbed as stratocumulus decks break up, over an area estimated to cover about 6.5% of the globe, is enough to cause a further ~8oC of global warming. After the stratocumulus decks have broken up, they only re-form once CO2 levels have dropped substantially below the level at which the instability first occurred.

These results point to the possibility that there is a previously undiscovered, potentially strong and nonlinear feedback, lurking within the climate system. These findings may well help to solve certain palaeoclimatic problems, such as the super-Hothouse climate of the Palaeocene-Eocene, some 50 million years ago. It's been hard to fully explain that event, given that estimates of CO2 levels at the time do not exceed 2,000 ppm. Present climate models do not reach that level of warmth with that amount of CO2. But the fossil record presents hard evidence for near-tropical conditions in which crocodilians thrived - in the Arctic. Something brought about that climate shift!

The quantitative aspects of stratocumulus cloud-deck instability remain under investigation. However the phenomenon appears to be robust for the physical reasons described by Schneider and co-authors. Closer to the present, the recent acceleration of global warming may be partly due to a decrease in aerosols. Aerosols produce smaller and more numerous cloud droplets. These have the effect of increasing the reflectivity and hence albedo of low cloud-tops (fig. 3). It follows that if aerosol levels decrease, the reverse will be the case. Of considerable relevance here are the limits on the sulphur content of ship fuels, imposed by the International Maritime Organization in early 2015. These regulations were further tightened in 2020. An ongoing fall in aerosol pollution, right under the marine stratocumulus decks, would be expected to occur. As a consequence, the size and amount of cloud droplets would change, cloud top albedo would decrease and there would be increased absorption of solar energy by Earth. That would be on top of the existing greenhouse gas-caused global warming. James Hansen discussed this in a recent communication (PDF) here.

Cloud effects on Earth's radiation.

Fig. 3: NASA graphic depicting the relationship between clouds, incoming Solar radiation and long-wave Infrared (IR) radiation. High clouds composed of ice crystals reflect little sunlight but absorb and emit a significant amount of IR. Conversely low clouds, composed of water droplets, reflect a great deal of sunlight and also absorb and emit IR. Any mechanism that reduces low cloud-top albedo will therefore increase the sunlight reaching the surface, causing additional warming.

In their Sixth Assessment Report, the IPCC also points out that the concentration of aerosols in the atmosphere has markedly increased since the pre-industrial era. As a consequence, clouds now reflect more incoming Solar energy than before industrial times. In other words, aerosols released by human activities have had a cooling effect. That cooling effect has countered a lot of the warming caused by increases in greenhouse gas emissions over the last century. Nevertheless, they also state that this counter-effect is expected to diminish in the future. As air pollution controls are adopted worldwide, there will be a reduction in the amount of aerosols released into the atmosphere. Therefore, cloud-top albedo is expected to diminish. Hansen merely suggests this albedo-reduction may already be underway.

Last updated on 15 October 2023 by John Mason. View Archives

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Argument Feedback

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Additional viewing

To explore this complex topic further, this is a great TED talk by climate scientist Kate Marvel:

Denial101x video(s)

Here is the relevant lecture-video from Denial101x - Making Sense of Climate Science Denial

Additional video from the MOOC

Expert interview with Steve Sherwood

Comments

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Comments 126 to 150 out of 271:

  1. Sphaerica (RE: 116), "115, RW1, The surface cannot be "getting" 517 watts in, as it's only emitting 396 W/m^2. You are ignoring the 23 reflected, 17 transported through thermals and 80 transported through evapotranspiration (396 + 23 + 17 + 80 = 516)." No, I'm not ignoring them. The 23 reflected is part of the albedo and not included in the 239 W/m^2 coming in. Latent heat and thermals are kinetic and not radiative, so the net effect they have on the radiative budget is zero. All the energy entering and leaving the system is radiative. This seems to be a major source of confusion on a multitude of issues. The surface is not getting 516 watts in, as if it was, the surface would be radiating 516 instead of 396. "The 239 comes from ignoring the reflected incoming radiation, which for all intents and purposes never affects the system. So 341 in - 102 reflected = 239. Similarly, 341 out - 102 reflected = 239. Everything balances." Where is the surface emitted of 396 W/m^2 in your numbers? You have to show how the surface is receiving this many watts with 239 entering and 239 leaving. All the energy has to be accounted for, and you can't simply create an additional 120 watts out of nothing (516 - 396 = 120).
  2. Sphaerica (RE: 115), "113, RW1, 'From the ISCCP data, which says that clouds cover 2/3rds of the surface. This means 1/3rd of the surface is clear sky (i.e. cloudless).' No. The ability of clouds to absorb IR is different from "clear sky" (i.e. the atmosphere)." I know - that's the whole point of separating the clear from the cloudy sky, as I did. "One cannot simply take a percentage. It's a meaningless estimation." Relative to the whole of the energy flow from the surface to space, the percentage of clear vs. cloudy sky is what matters. " If my calculations are in error, why do they accurately predict the correct brightness temperature of 255K? Where do you do that, and how?" At the end of my post #2.
    Response: [mc] Fixed closing italics tag.
  3. 126, RW1,
    All the energy entering and leaving the system is radiative. This seems to be a major source of confusion on a multitude of issues.
    All of the energy entering/leaving from space is radiative. That does not allow you to ignore other energy transfers between the surface and atmosphere. Those are not inconsequential. It's an "energy budget," not a "radiation budget." The diagram covers the movement of energy in a three layer model (surface, atmosphere, space). The only way for energy to get in from and out to space is radiative, but that does not apply to transfers between the surface and atmosphere. All energy transfers must be accounted for. You can't simply choose to ignore some numbers. Why do you think things add up properly when they are included, and don't when they are excluded?
    Where is the surface emitted of 396 W/m^2 in your numbers?
    I gave this in post 110, but to repeat and clarify... If you want to consider the atmosphere in total, it gets 79 in from space which is reflected back (a wash). 23 are reflected through from the surface and can also be ignored (a wash), as does the 40 that passes through radiated from the surface. That leaves us with, coming from the surface, 17 from thermals, 80 from evapotranspiration/latent heat, and 356 absorbed through radiation (we've already recognize the 40 that passes through, so we don't work with the whole 396, just the remaining 356), for a total coming into the atmosphere from the surface of 17 + 80 + 356 = 453. Another 78 are absorbed from inbound sunlight, from space, giving a total absorbed by the atmosphere of 531. The atmosphere emits 333 down to the surface as radiation, and 199 (169 from the atmosphere, 30 from clouds) up into space, for a total of 532. So the atmosphere gets 531(532) from above and below, and sends out 532(531) up and down, but not in equal measure (if it did the surface of the planet would be 255˚K, and we'd all be dead, or else we'd be ice-loving lifeforms huddling around geothermal vents in the deep ocean). We can't keep going around and around with this. It's a simple diagram. Sit down with a piece of paper and add the numbers up. It's really not that hard.
  4. Sphaerica (RE: 117), "2) Do you have any response to the question that I've posed 3 times (posts 27, 71, 90) and KR once (post 94)? For the fifth time, do you have any response to the fact that multiple studies, using a wide variety of methods, all point to a climate sensitivity of 3 or greater, and so the chance of cloud feedbacks being negative or neutral is slim to none?" Look, I can only deal with one thing at a time. There are many facets to this whole thing - each of which involve a significant degree of complexity. I can eventually address those things in their appropriate threads.
  5. 126, RW1,
    At the end of my post #2.
    As before, I cannot make heads or tails of those numbers. I can see, though, that you are trying to distinguish clear and cloudy sky in your numbers, and since we have already established that that information is not available in Trenberth's diagram, I can dismiss it as inaccurate. If you'd still like to explain that set of numbers, you can try, but please be clear. What you have now is not. But to give you a generic answer to your "why do they accurately predict" query, if your numbers come to 239 at TOA (no matter how you got there) you are going to get 255K. If they come to 390-396 from the surface, you're going to get 288K-289K. That running your calculations in reverse brought you back to these numbers is no big surprise, but doesn't validate the logic behind the calculations.
  6. 126, RW1,
    Look, I can only deal with one thing at a time.
    Apologies, but you cannot one the one hand claim that there is other evidence for negative cloud feedbacks (without producing it), and on the other ignore the contrary evidence (neatly summarized and cited by SS) provided as rebuttal. But I will agree, we should continue to focus on your numbers, and your interpretation of Trenberth's diagram, as I believe that is where you will get the greatest insight into where you are mistaken. Once we get past that, we can revisit your position on the issue by considering other factors.
  7. Quick correction. At the end of post 128, I incorrectly said the temp would be 255˚K if the atmosphere radiated heat equally in both directions. The actual temperature would be 262˚K. We'd still be ice-loving creatures living in the ocean depths near geothermal vents, but we wouldn't be quite as ice-loving as I implied.
  8. RW1 - "Look, I can only deal with one thing at a time. ... I can eventually address those things in their appropriate threads. " I would like to point out that this is the "What is the net feedback from clouds" thread - that in fact is the appropriate topic here, not various interpretations of the Trenberth energy budget. Looking up the dynamic feedback numbers in the Trenberth diagram, let's see... Look! Nothing! There is no dynamic information, nothing about net feedbacks, nothing about how various elements change with temperature, in the Trenberth diagram!
  9. Sphaerica (RE: 130), "All of the energy entering/leaving from space is radiative. That does not allow you to ignore other energy transfers between the surface and atmosphere. Those are not inconsequential. It's an "energy budget," not a "radiation budget." The diagram covers the movement of energy in a three layer model (surface, atmosphere, space). The only way for energy to get in from and out to space is radiative, but that does not apply to transfers between the surface and atmosphere. All energy transfers must be accounted for. You can't simply choose to ignore some numbers." I'm not ignoring anything. Nor am I claiming the kinetic energy flows of latent heat and thermals from the surface to the atmosphere aren't part of the whole thing. They are. The problem lies in that Trenberth returns the energy from latent heat and thermals to the surface as 'back radiation' when in reality most of it returns in kinetic form through precipitation. The bottom line is it's returned to the surface in equal and opposite amounts, so relative to the radiative budget and COE, its net effect is zero. If any of the kinetic energy moved from the surface into the atmosphere gets radiated into the atmosphere and ultimately radiated out to space, the amount returned to the surface will be less than the amount that left the surface. This will cool the surface and reduce surface emitted radiation by and equal and opposite amount. Again, this seems to be a major source of confusion. In Trenberth's diagram, the latent heat and thermals of 97 are returned to the surface as 'back radiation'. The incoming solar energy of 78 'absorbed by the atmosphere' is also brought to the surface as 'back radiation'. But it's not really 'back radiation' - it's 'forward radiation' yet to reach the surface that last originated from the Sun. The point is 239 W/m^2 from the Sun gets to the surface and becomes 396 through 157 of back radiation from the atmosphere. 333 - 97 - 78 = 158 coming back from the surface emitted of 396. 239 arriving at the surface from the Sun + 157 arriving at the surface from back radiation from the atmosphere = 396 emitted at the surface. From the surface, 70 passes through the atmosphere unabsorbed out to space and 169 is emitted by the atmosphere up out to space. 70 + 169 = 239 leaving at the TOA.
  10. Sphaerica (RE: 128), "Another 78 are absorbed from inbound sunlight, from space, giving a total absorbed by the atmosphere of 531." The atmosphere cannot create any energy of its own. COE dictates this. You can't have 531 absorbed by the atmosphere when only 239 W/m^2 are coming in and the surface is only emitting 396 W/m^2.
  11. 134, RW1,
    ...when in reality most of it returns in kinetic form through precipitation...
    No, this is wrong. The kinetic energy isn't part of the equation. You're right, it's lifted up, and then falls down. What is being transported is the heat. Thermals are bodies of air that are heated by the surface, and rise. The heat doesn't fall back down through the pull of gravity. It stays in the atmosphere until it is radiated away. Evapotranspiration puts the energy into vaporizing the water. When the water condenses in the atmosphere, that energy is released -- to the surrounding atmosphere -- as latent heat. When the rain falls, it's a cool rain, having left its heat behind in the atmosphere.
    In Trenberth's diagram, the latent heat and thermals of 97 are returned to the surface as 'back radiation'.
    Okay, so if you got this, what was the "kinetic energy" bit about? But you are wrong in saying it is returned to the surface. The same goes for the energy absorbed by the atmosphere from the sun. You can't say where it goes versus other energy. The atmosphere is a big pot, and all of the energy is part of the stew. Once it's been added, you can't say "this part of the broth came from here and has to go there."
    239 arriving at the surface from the Sun + 157 arriving at the surface
    I have told you repeatedly. You are making the 157 number up. You cannot extract that with the information given. We need to stop discussing this. If you can't interpret the diagram properly, you certainly can't out think all of the climate scientists. Sit down and work this stuff out. Don't start by assuming you're smarter than everyone. Start by assuming you are the student, and there is something here you don't get. Stop trying to second guess it. Work through the numbers. Understand the diagram. If you can do that, and we can move beyond this, we can discuss negative cloud feedbacks. We've already overloaded this threat with analyzing Trenberth's diagram (for the sake of analyzing your numbers on negative cloud feedbacks) and we're getting nowhere.
  12. (RE: my 134), I wrote: The point is 239 W/m^2 from the Sun gets to the surface and becomes 396 through 157 of back radiation from the atmosphere. 333 - 97 - 78 = 158 coming back from the surface emitted of 396. This should say: The point is 239 W/m^2 from the Sun gets to the surface and becomes 396 through 157 of back radiation from the atmosphere. 333 - 97 - 78 = 158 coming back to the surface for a total of 396 (239 + 158 = 396) (Trenberth purposefully has an extra watt in there).
  13. Sphaerica (RE: my 136), "[The kinetic energy isn't part of the equation]. You're right, it's lifted up, and then falls down. What is being transported is the heat. Thermals are bodies of air that are heated by the surface, and rise. The heat doesn't fall back down through the pull of gravity. It stays in the atmosphere until it is radiated away. Evapotranspiration puts the energy into vaporizing the water. When the water condenses in the atmosphere, that energy is released -- to the surrounding atmosphere -- as latent heat. When the rain falls, it's a cool rain, having left its heat behind in the atmosphere." Thermals and latent heat are in the form of kinetic energy. They are totally separate from and in addition to the 396 emitted radiatively by the surface. I do not dispute that some of the kinetic energy moved from the surface to the atmosphere is radiated into the atmosphere and finds its way radiated out to space. Regardless of whether it's most or only a small amount (Trenberth has all of it being returned), it's net effect is still zero on the radiative budget. I think you may not understand that the surface is emitting 396 solely due to its temperature and nothing else. As a result, it cannot be receiving more energy than this.
  14. @Sphaerica RW1 has made 52 comments to this post, so far. Virtually none of that deserves a reply. He or she went on commenting virtually because you continue to reply to him/her. In my opinion it is most of all off-topic because all those additions and subtractions don't make to "feedback". I don't want to point nothing specifically because I didn't read -nor did nor will, most of the visitors- that ping-pong of some 100 of comment. I'm saying I don't want to point, but I suspect that somebody might try to get some 70W/m2 reflected upwards and some whatever, say, 40W/m2 downwards and "declare" a negative feedback from that when the feedback resides in the change of cloudiness, the type of clouds and the altitude of the clouds so those 70/40 would change maybe to 71/42 or maybe to 72/38 what provides the feedback and its sign. I'm not sure what are you two discussing, but I don't see in Trenberth's figure nor in those finger calculations the feedback that may confirm or falsify the myth subject of this post. If you stop replying I think RW1 messages will end the same way foam vanishes once shaking ceases.
    Response: [muoncounter] This is deja vu all over again; by the standards of the Lindzen and Choi thread, its just getting warmed up.
  15. Sphaerica (RE: my 136), "But you are wrong in saying it is returned to the surface. The same goes for the energy absorbed by the atmosphere from the sun. You can't say where it goes versus other energy. The atmosphere is a big pot, and all of the energy is part of the stew. Once it's been added, you can't say "this part of the broth came from here and has to go there." You can derive them with the constraints COE puts on the system. There is only one source of energy - the Sun. You can't count energy twice, which is what Trenberth does in the diagram by designating 78 being absorbed by the atmosphere and also having it part of the 333 of back radiation to the surface. The atmosphere cannot create any energy of its own - the energy either last originated from the Sun or surface emitted.
  16. Sphaerica (RE: 130), "As before, I cannot make heads or tails of those numbers. I can see, though, that you are trying to distinguish clear and cloudy sky in your numbers, and since we have already established that that information is not available in Trenberth's diagram, I can dismiss it as inaccurate." Only the cloudy vs. clear sky percentages don't come directly from Trenberth's diagram. Everything else is taken directly from the diagram, as I've explained (or tried to at least). "That running your calculations in reverse brought you back to these numbers is no big surprise, but doesn't validate the logic behind the calculations. That's true, but the point is all the calculations work out with the all 'logic' I've used, and the criticisms of the 'logic' don't work out, as I've shown. For example, it was claimed the 169 designated as being 'emitted by the atmosphere' was for the clear sky, but that doesn't work because only 131 W/m^2 is actually emitted to the clear sky. Can you find a better way to quantify the relationships in a way that results in the appropriate output power and brightness temperature of 255K?
  17. @muoncounter response to #139 Oh! I see (my Goodness). So, why not a Yogi Berra section? For instance, one of the last comments telling something like "a body that emits energy solely due to its temperature cannot be receiving more energy than that" or "if the square doesn't fit the circular hole then take a drop hammer and, smash it!".
  18. RW1, We're done. As muoncounter and Alec have pointed out, I've shown way too much patience, and you quite simply don't get it... seemingly because you refuse to. I can't help you with that. The diagram is very, very simple. It's really not all that hard to understand, and that you ever thought you had the genius to prove all of climate science wrong through your clever re-interpretation of it just astounds me. You should put less time into your clever numbers, and more time into reading up on the physics behind climate science. It would help you tremendously, and the number of misconceptions and misunderstandings you hold now seem enormous -- they're holding you back. Really, the mods should go back and delete every single post, because almost none of them relate in any way to cloud feedback, and where they do, they're tainted by your misinterpretation of Trenberth's simple energy budget diagram. Conversation ends.
  19. Sphaerica (RE: 143), "We're done. As muoncounter and Alec have pointed out, I've shown way too much patience, and you quite simply don't get it... seemingly because you refuse to. I can't help you with that. Conversation ends." Suit yourself. "Really, the mods should go back and delete every single post, because almost none of them relate in any way to cloud feedback, and where they do, they're tainted by your misinterpretation of Trenberth's simple energy budget diagram." All of the my posts are directly or indirectly related specifically to the cloud feedback issue. If anything, I was the one frequently pushing to keep the discussion on topic, while others digressed.
  20. Documentary evidence that cloud feedback is positive, courtesy of the good folks at the North Pole webcam site: Spring conditions can be cloudy at the North Pole. Clouds are produced when the North Pole experiences Spring warming and the beginning of Summer melting. Water is evaporated from the melting snow surface, forming the fog and low clouds that are seen in Spring/Summer pictures from the North Pole, such as the one on the right from June 2002. In the left image, from 5/1/02 19:06 UTC, the surface is covered by fog and low clouds. Radiation energy is trapped near the surface and thus the temperatures have increased to a very warm 27 F. -- emphasis added [source] Temperature inset at lower left shows 27F as stated.
  21. muoncounter (RE: 145), "Documentary evidence that cloud feedback is positive, courtesy of the good folks at the North Pole webcam site: Spring conditions can be cloudy at the North Pole. Clouds are produced when the North Pole experiences Spring warming and the beginning of Summer melting. Water is evaporated from the melting snow surface, forming the fog and low clouds that are seen in Spring/Summer pictures from the North Pole, such as the one on the right from June 2002. In the left image, from 5/1/02 19:06 UTC, the surface is covered by fog and low clouds. Radiation energy is trapped near the surface and thus the temperatures have increased to a very warm 27 F. -- emphasis added" It's not disputed that the cloud feedback is positive in areas that are permanently snow and ice covered, such as the North Pole. This is because the albedo of clouds is roughly the same as snow and ice, so the net effect of clouds is to warm by 'trapping' additional surface emitted energy. However, the vast majority of the Earth is not snow or ice covered, which is consistent with net negative feedback for clouds, globally. Also, when ice or snow melts from warming (CO2 induced or otherwise), the primary mechanisms that drive negative cloud feedback reassert themselves - specifically the latent heat of evaporation, which has a strong cooling effect on the surface, and the clouds above become more reflective than the surface, which also has a strong cooling effect.
  22. RW1#146: "the vast majority of the Earth is not snow or ice covered, which is consistent with net negative feedback for clouds" I don't know where you live, but in my neck of the woods, nights don't get cool when there's high humidity (which is almost always) or high clouds. But here's how an actual weatherperson puts it: Clouds are regions of a high density of saturated air, (which form cloud droplets). Clouds (especially low thick clouds) have a high ability to absorb and re-emit longwave radiation. Thus, on cloudy nights much less longwave radiation is able to escape to space. Holding in heat at night is a fingerprint of the enhanced greenhouse effect. So your thesis that clouds will always be negative feedbacks doesn't hold water.
  23. 146, RW1,
    However, the vast majority of the Earth is not snow or ice covered, which is consistent with net negative feedback for clouds, globally.
    So you say, but you offer no (substantive) support that actually proves this. You keep saying there's a net negative cloud effect, but (1) you don't prove it, and (2) as several people have pointed out, the important factor isn't the net current effect, it's the net change as a result of warming. Similarly, your logic is only so much "thought experiment" with no substantive calculations. It's easy to say things like "strong cooling effect" without backing such statements with actual numbers.
  24. muoncounter (RE: 47), "I don't know where you live, but in my neck of the woods, nights don't get cool when there's high humidity (which is almost always) or high clouds. But here's how an actual weatherperson puts it: Clouds are regions of a high density of saturated air, (which form cloud droplets). Clouds (especially low thick clouds) have a high ability to absorb and re-emit longwave radiation. Thus, on cloudy nights much less longwave radiation is able to escape to space. Holding in heat at night is a fingerprint of the enhanced greenhouse effect. So your thesis that clouds will always be negative feedbacks doesn't hold water." Yes, net effect of clouds at night is to warm (or slow heat loss). This is because clouds are better at 'trapping' outgoing surface energy than the clear sky is. Again, this is not in dispute, nor does it conflict with net negative feedback for clouds. Globally averaged data automatically includes the effects of night and day.
  25. Sphaerica (RE: 148), "You keep saying there's a net negative cloud effect, but (1) you don't prove it," I've provided much evidence and logic for net negative cloud feedback. Even Dessler says in his paper the net effect of clouds is to cool by 20 W/m^2. "(2) as several people have pointed out, the important factor isn't the net current effect, it's the net change as a result of warming." I'm aware of this, but I'm not the one making the claim that the net effect of clouds is suddenly going to switch from cooling to warming on the next few watts incident on the surface.

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